A zero-emission treatment system for low-energy evaporative gas at lng receiving station

Abstract

The invention relates to a low-energy-consumption zero-emission evaporated gas treating system of a liquefied natural gas (LNG) receiving station. The characteristics that wharf unloading pipelines need to be opened in normal operation working conditions and intermittent zero outward conveying working conditions of the LNG receiving station for cold insulation circulation are utilized, an LNG refrigerating branch is arranged on a cold insulation circulation pipeline of the existing wharf discharging pipeline of the LNG receiving station, LNG is led out from the cold insulation circulation pipeline and further cooled by aid of a refrigerating device, and the cooled LNG is fed back to a previous pre-cooling spraying system at the top of an LNG storage tank and sprayed into the LNG storage tank through the previous pre-cooling spraying system, so that boiled off gas (BOG) in the tank can be absorbed, and zero-emission treatment of the BOG can be achieved. The low-energy-consumption zero-emission evaporated gas treating system is particularly suitable for peak adjusting type LNG receiving stations, can ensure safe operation of the system under the working conditions of intermittent zero outward conveying, can avoid huge waste caused by the traditional BOG discharging depressurizing mode and has outstanding economic benefit.

Description

technical field [0001] The invention relates to an LNG receiving station boil-off gas processing system, in particular to a low-energy-consuming boil-off gas zero-emission processing system of an LNG receiving station that can operate under the intermittent zero-transport working condition of the LNG receiving station. Background technique [0002] LNG (liquefied natural gas, liquefied natural gas) is a low-temperature fluid. Although LNG equipment has good insulation measures, a certain amount of BOG will inevitably be generated in it due to external heat transfer and system cooling requirements during storage and operation. (BoiledOffGas, BoiledOffGas). As the amount of BOG increases, the temperature and pressure inside the LNG storage system will increase accordingly. When the internal pressure of the LNG storage tank is higher than the safety relief pressure set by the system, the safety valve on the top of the LNG storage tank opens, and the BOG is directly released to...

AI Technical Summary

Problems solved by technology

Since the natural evaporation and production of BOG is not a stable process, it is necessary to shut down the BOG direct liquefaction device repeatedly, and it usually takes 3 to 5 hours for the BOG direct liquefaction device to start and run, which makes the actual operation difficult and easily causes the system pressure to become unstable. If the pressure of the LNG storage tank is too low, additional gas supply and pressure maintenance are required

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